The present invention relates to treated inorganic pigments used in thermoplastic formulations.
Often such pigments are incompatible with the thermoplastic binders in which they are incorporated. Such incompatibility can be manifested by failure of the pigment to uniformly disperse in the binder, for example. Pigmentary inorganic pigments, such as pigmentary titanium dioxide, generally do not exhibit the desired pigmentary properties in the binder due to such incompatibility and can interact with phenolic anti-oxidants in polyethylene, for example, causing yellowing of the pigmented polyethylene product.
One aspect of the invention is a treated inorganic pigment which is resistant to agglomeration under storage conditions and disperses evenly and uniformly in various binders into which it is incorporated. Another aspect of the invention is a treated pigmentary titanium dioxide pigment which imparts excellent pigmentary properties to the binder. A further aspect of the invention is a method for suppressing yellowing in polyethylene or like polyolefin plastics by utilizing the disclosed treating agent either as a stabilizer added to the polyethylene or as a treating agent applied to the titanium dioxide pigment incorporated into the polyethylene. These and a variety of other aspects of the invention will become apparent from the following description of the invention.